This invention relates to crimping of yarn and more particularly, it relates to an apparatus for crimping and a method for controlling the apparatus.
Stuffer box crimpers are well known and have been widely used for crimping yarns, tows and threads.
The yarn is introduced with the aid of a pair of rollers into a crimping chamber in which it becomes accumulated until its pressure is sufficient to overcome the pressure of the counter pressure device; e.g., a hinged flapper, preventing it from leaving the chamber. In some instances it has been found desirable to introduce into the stuffer crimper chamber a heated fluid under pressure such as steam and utilize the steam to not only assist the crimping process by providing heat and moisture to the yarn in the crimping chamber but also to control the hinged flapper at the outlet of the crimping chamber.
In a stuffer box crimping process, newly delivered yarn is continuously and mechanically stuffed directly onto the top of previously crimped yarn in a filled stuffer chamber, thereby exerting an immediate buckling-type crimping force onto the new yarn. Since there is essentially no space above the yarn within the filled stuffer chamber, the newly introduced yarn is limited to receiving only a folded or two-dimensional crimp due to the buckling forces. It would be advantageous to provide in a crimping chamber process an apparatus and method for providing a space above the yarn previously compacted within the stuffer chamber so that newly introduced yarn is not subjected immediately to buckling-type crimping forces but allowed to develop instead a three-dimensional crimp therein.